Immunohistochemical evaluation ofkeratin 20 expression inintestinal metaplasia typesItoIII

Aims-To investigate differences inexpressionof keratin20,a cytoskeletal protein ingastrointestinal epithelial cells, in completely differentiated intestinal metaplasia (type I)andincomplete metaplasia (types IIandIII). Methods-Gastric biopsy specimens from 66patients withintestinal metaplasia were analysedimmunohistochemically. Expression ofkeratin 20wasquantified as thepercentage ofimmunoreactive cells on thetips, theupper, anddeepfoveolae. Results-In allspecimens keratin 20was foundonthetips andintheupperfoveolae ofintestinal metaplasia. Keratin20was notobserved inthedeepfoveolae. Nodifferences wereseenbetweentheantrum andthebody.Expression patterns were comparable betweentypesIandIII.In typeII,however, lowerimmunoreactivity wasfound.Boththedifferences between typesIandIIaswellasbetweentypesII andIIIweresignificant (p< 0.05). Conclusions-Keratin 20isexpressed in metaplastic mucosaasaresult ofintestinaldifferentiation. Positive staining found exclusively injuxtaluminal cells occurs onlyinmaturecells containing keratin 20. Loweredimmunoreactivity in typeII comparedwithtypesIandIIIindicates thedifferent natureoftypeIIintestinal metaplasia. Further studies areneededto shedlighton thebasicfundamental mechanismresponsible forthis. (iClinPathol 1996;49:791-794)